1. Technical Field of the Invention
The present invention relates to the self servo writing disk drives and related methods.
2. Description of Related Art
As is known, many varieties of disk drives, such as magnetic disk drives are used to provide data storage for a host device, either directly, or through a network such as a storage area network (SAN) or network attached storage (NAS). Typical host devices include stand alone computer systems such as a desktop or laptop computer, enterprise storage devices such as servers, storage arrays such as a redundant array of independent disks (RAID) arrays, storage routers, storage switches and storage directors, and other consumer devices such as video game systems and digital video recorders. These devices provide high storage capacity in a cost effective manner.
As a magnetic hard drive is manufactured, portions of the disk are prerecorded at the factory. A plurality of servo spirals are written to the disk in spiral patterns that begin from the innermost to the outermost writeable section of the disk. In addition, a plurality of servo wedges are written to the disk contained in radial segments about the disk. For each track on the disk, each servo wedge contains a servo field that is recorded with a preamble, a synchronization mark and servo data. Examples of servo data include a servo address mark, wedge number, track number, and burst data used by a disk controller to control the rotation of the disk and the position of the read/write heads of the disk drive. Given the need for highly accurate positioning, these servo spirals and servo wedges are traditionally recorded on the disk using a servo writer. Given a desire to minimize the use of the servo writer, certain self servo writing disk drives write the servo spirals and only a certain number of seed servo wedges, with the remaining servo wedges being written to the disk by the disk drive itself.
A sizable market has developed for these devices and the price per unit of storage has steadily dropped. Modern host devices are provided with greater storage capacity at reduced cost, compared with devices that where manufactured a few years earlier. The need exists for provide hard drives that can be manufactured efficiently on a mass scale with high accuracy.